Purpose. Retinal degenerations (RD) such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD) destroy the outer retinal layers, but can spare the ganglion cells. We have been evaluating the feasibility of bypassing damaged photoreceptors and electrically stimulating the remaining viable retinal layers as a means to provide limited visual input to a subset of patients blind from severe outer retinal degeneration (ORD). Methods. Using a pars plana approach, focal electrical stimulation of the inner retinal surface with brief charge-balanced pulses was performed. Custom built intraocular electrodes coupled with an optically isolated, constant current generator were used to deliver the pulses. The procedure was performed in 5 subjects with bare or no ligit perception vision (3 had RP, 1 AMD, and 1 unspecified RD from birth). Results. Stimulation elicited a visual perception of a spot (phosphene) which was retinotopically correct in 4/5 subjects who had had previously useful vision. Two subjects could perceive two simultaneous phospheres upon independent stimulation with 2 electrodes. In a resolution test, one subject resolved phosphenes at 1.75° center-to-center distance (approx. 4/200 visual acuity). One subject could also identify the shape of thestimulating electrode. Conclusions. These findings demonstrate that local electrical stimulation of the inner retinal surface in patients blind from RD's results in focal light perception. Such findings in an acute experiment warrant further research into the possibility of prolonged retinal stimulation, improved resolution, and ultimately an intraocular visual prosthesis.
|Original language||English (US)|
|Journal||Investigative Ophthalmology and Visual Science|
|State||Published - Feb 15 1996|
ASJC Scopus subject areas
- Sensory Systems
- Cellular and Molecular Neuroscience